Manufacturing

Getting the Wind Up

Wind turbines have been the source of controversy in one form or another since they started to appear on our landscape, with the press not helping matters by running endless scare stories, often involving safety issues. Strathclyde University in Glasgow is helping dispel doubts over gearbox safety and reliability by commissioning a test bed to evaluate various aspects of the transmission. Pirtek Glasgow has played a major part in its construction.

"The programme we are running at present is a 10,000 hour study to simulate how the oil in the gearbox degrades with age and use,” says Senior Integration Manager, John Paschke. "The data from this study will show how this affects mechanical elements in the gearbox. It will be one of several long term studies we will undertake that will include all aspects of the gearbox. The next being an evaluation of the bearings.”

Paschke reports that the new test bed is a world first and is, therefore, charting new waters. “No-one has built such a complex test rig as this with such a wide array of sensors. Although we had a very precise set of design drawings it was obvious as the rig was constructed that changes would have to be made. So I'm very pleased to have had Pirtek Glasgow involved right from the start. They advised and provided all the hydraulic hoses, fittings and gauges in the construction of the rig,” he says. “They started work in August with one MSST who had to transport all the equipment from the service van parked outside, hundreds of metres through the corridors to the university. As work progressed and changes were made, Pirtek often had three engineers on site to ensure the test rig was completed on time."

According to Paschke, the findings of the test rig are eagerly awaited by a number of interested parties, and not just the wind turbine fraternity. "There are several third parties that are extremely interested in the accelerated stress tests as it will enable them to increase the lifetime of the gearbox, by decreasing the load patterns on the unit as it ages,” he explains. “Obviously the oil companies are also keen to understand how the oil degrades and the impact that has on every component's wear.”

The sensor technology encompassed in the rig will be fed into a huge and very comprehensive database. The data will be part of the existing auto associative neural network, which will identify defects that are out of trend with existing data. The rig will operate at between 85 and 110 percent of the normal parameters on a three second on, 30 second flat and three second wind down cycle. The static loading programme will see a 90 kW motor driving a 200 kW test in a close-coupled feedback loop.

"The lube system is fitted with a scavenging system that can force oil into the gearbox at higher flow rates or suck oil out making the oil work much harder. We can then examine the component interfaces especially the bearings to see how the oil meniscus is affected,” Paschke adds. “The unique features of the rig include the sheer number of sensors. We have three optical sensors IR spectrum, visible light spectrum and the third looking at particle count and sizing. Another is the Tandelta which looks at the electrical conductivity. All of this will help predict how to set the turbine up for wind about to hit the turbine, to tailor the turbine power against aging. All this will help calculate the output relating to the wind to maximise performance of the turbine."

John Paschke is quick to point out the role that Pirtek has played in what is a pioneering development for the wider wind power sector. "I've been delighted with how Pirtek has performed. I've established a very good relationship with the centre and the engineers and they have always been there when I've needed to change things,” he concludes. “They have supplied everything I've need on this rig and I'm very pleased with how it has performed. It will be a real boom to the industry."